Process for synthesizing a multicomponent acidic catalyst composition by an organic solution method

ABSTRACT

A process for preparing a catalyst composition wherein a Metal Hydrocarboxide I, such as aluminum secbutoxide, a Metal Hydrocarboxide II, such as silicon ethoxide, an acidic phosphorus-oxygen composition, such as phosphoric acid, and water, are reacted in the presence of a liquid organic medium, such as acetone, to form a catalyst precursor composition, which is then calcined to form the catalyst, is disclosed. The catalyst is useful for condensing carboxylic acids or their ester with aldehydes or acetals to synthesize α, β-ethylenically unsaturated acids or esters, such as methylmethacrylate.

BACKGROUND OF THE INVENTION

The present invention relates to acidic catalyst compositions, theirpreparation, and use to synthesize, for example α,β-unsaturatedcarboxylic acids, their functional derivatives, or olefinicoxygen-containing organic compounds.

It is known that olefinic compounds can be synthesized by reactingaldehydes or acetals with organic compounds containing carbonyl groupssuch as carboxylic acids, esters, aldehydes, and ketones. Such reactionscan be illustrated by the following equations: ##STR1## It will be notedthat equations 1 and 2 use formaldehyde or methylal, respectively, asalternative reactants. These are conventional reactants which are eachassociated with certain disadvantages depending on the choice ofcatalyst. Catalysts employed for the reactions of equations 1 or 2 canbroadly be classified as basic or acidic. It is well known, that basiccatalysts, when employed in conjunction with reaction of equation 1,will cause disproportionation of formaldehyde to H₂, CO₂, and methanol,in accordance with the Cannizzaro reaction thereby reducing theselectivity of the reaction to desired products such asmethylmethacrylate (MMA) and/or methacrylic acid (MA). In addition, theuse of a basic catalyst also causes decarboxylation of the co-reactantcarboxylic acid or ester thereof whether formaldehyde is employed as areactant or not, thereby further reducing the selectivity to desiredproducts. Furthermore when formaldehyde is manufactured in the vaporphase, it is adsorbed and dissolved in water to reduce its potential topolymerize. Methanol is also employed as a polymerization inhibitor.Consequently, formaldehyde is generally sold economically as a 35-45wt.% mixture of the same with the remainder being water and methanol.The presence of such large amounts of water and methanol makes itdifficult to economically achieve a concentrated reactant feed stream.In view of the disadvantages of the base-catalyzed formaldehyde basedsynthesis route, attempts have been made to replace formaldehyde with aless troublesome reactant such as dimethoxy methane, also known asmethylal. However, when methylal is employed in conjunction with a basecatalyst, conversion of methylal is very low. Such low conversions arebelieved to be attributable to the inability of the basic catalyst toefficiently hydrolyze the methylal to formaldehyde which in turn reactswith the carboxylic acid or ester co-reactant. This problem has beenalleviated to some extent by the use of acid catalysts. However, evenwith conventional acid catalysts, the conversion of methylal is stillwell under 100%. Furthermore, it has been reported (see Albanesi et aldiscussed hereinafter) that certain acid catalysts also lead todecarboxylation of, for example, methylpropionate producing CO₂ anddimethyl ether.

Obviously, the most efficient use of methylal would be to convert 100%thereof to MMA and/or MA while keeping coreactant decarboxylation to aminimum. Such high efficiency reactions are difficult, however, toachieve in practice. A suitable and relatively economic alternativewould be to produce reusable by-products which could be recycled in asefficient manner as possible. One reusable by-product from methylal isformaldehyde. However, when less than 100% conversion of methylaloccurs, optimum use of process credits would necessitate recovery andrecycle not only of formaldehyde, but also of unconverted methylal. Thiscomplicates the recycle procedure relative to the recycle offormaldehyde alone. Furthermore, if one seeks to recycle formaldehyde,the decomposition thereof to CO, and H₂ must also be minimized. Similarconsiderations apply to the undesired decarboxylation reactions whichalso produce unusable products that cannot be recycled.

Accordingly, and in view of the above it would be of extreme economicsignificance if a catalyst could be developed which is capable ofemploying either methylal or formaldehyde as a reactant for theproduction of α,β-ethylenically unsaturated products for carboxylicacids or their derivatives without, or with at least reduced, attendantundesirable side reactions which occur when employing conventionalacidic or basic catalysts.

Various processes and catalysts have been proposed for theaforedescribed reactions.

For example, U.S. Pat. No. 3,100,795 describes the use of basiccatalysts such as natural or synthetic (e.g. zeolites), alkali andalkaline earth metal aluminosilicates, as well as alkali and alkalineearth metal hyroxides supported on natural or synthetic aluminosilicatesor silica gels, to catalyze the reaction between methanol, propionateacid, and formaldehyde to form methylmethacrylate. The conversion tomethylmethacrylate based on formaldehyde is reported in Example 5 as 66%and the yield is reported as 99%, although such terms as conversion andyield are left undefined in this patent. Neither the catalysts of thepresent invention nor the method of its preparation are disclosed inthis patent.

U.S. Pat. No. 3,840,588, assigned to Monsanto, describes the use ofalkali metal hydroxides or oxides dispersed on a support having asurface area of 350 to 1000 m² /gm. Suitable support materials includealuminas, thorias, magnesias, silica-aluminas, and silicates. Inaddition to hydroxides or oxides, other alkali metal compounds may bedeposited on the support such as carbonates, nitrates, sulphates,phosphates, inorganic salts, acetates, propionates or othercarboxylates. All of such supported catalysts are basic catalysts and noreaction between the catalysts and their supports is even alleged,simple impregnation procedures being employed for deposition. Thesecatalysts are employed in the reaction of formaldehyde and saturatedalkyl carboxylates to form α,β-ethylenically unsaturated esters attemperatures of at least 400° to 600° C. A methylmethacrylateselectivity of 82 mole % at formaldehyde conversions of 98% are reportedin this patent at a reaction temperature of 400° C. and a space timeyield of 490 L/hr (Table II, Run 7). However, at 430° C. and higherspace time yields of 960 L/hr (Example 1) the selectivity tomethylmethacrylate of 92 mole % is obtained at a formaldehyde conversionof only 67%. At reaction temperatures below 400° C., it is alleged thatselectivities drop significantly, e.g., to below 40% (see FIG. 2) due tothe Cannizzaro reaction (Col. 3, Lines 29 et seq). Moreover, water mustbe employed in the feed stream in strictly controlled amounts to obtaingood selectivity. In the absence of water, formaldehyde conversion isnegligible, and in the presence of too much water selectivity dropsdrastically. The required use of water necessitates the use of alcoholsin the feed stream to suppress hydrolysis of the ester reactant andreduce the amount of ester in the reaction zone by acting as a diluent(see Col. 3, Lines 55 et seq) as well as complicating the overallprocess to implement strict control of the water content of the feedstream. This control of water content can be further complicated by thein-situ production of water in the reactor. Thus, selectivities andyields achieved in this patent are obtained at the sacrifice ofsimplicity of process design and overall process economics.

U.S. Pat. No. 3,933,888, assigned to Rohm and Haas Co., discloses thereaction of formaldehyde with an alkanoic acid or its ester in thepresence of basic catalysts containing basic pyrogenic silica (e.g. SAof 150 to 300 m² /g) alone or impregnated with activating agents whichprovide additional basic sites to the pyrogenic silica when calcined.Such activating agents include alkali and alkaline earth metalhydroxides, oxides, amides, and salts such as carbonates, oxalatesphosphates, e.g., Na₃ PO₄, Na₂ HPO₄, KOCH₃, Na₄ SiO₄. The identity,impregnation, and calcination procedures, of the activating agent isalways selected to provide a basic catalyst. A molar ratio of alkanoicacid:formaldehyde:water:methanol of from 1:1:0.01 to 1:1:6:0.03 isdisclosed. With a molar ratio of propionicacid:formaldehyde:water:methanol of 20:20:50:1 and a maximum of 34%conversion of formaldehyde and propionic acid to methacrylic acid andmethylmethacrylate, selectivities (referred to in this patent as yields)to MA+MMA no greater than 69%, based on formaldehyde converted, or 80%,based on propionic acid converted, are achieved. When reacting methylpropionate with formaldehyde, water and methanol in the same molarratio, the selectivity to MA+MMA based on a formaldehyde conversion of25% is 63% (see Ex. 24). Furthermore, from the data of Table III in thispatent, it can be calculated that for every 100 moles of formaldehyde inthe feed, 34 moles thereof are converted to MA+MMA, and 45 moles thereofremain unreacted. About 21 moles of formaldehyde are unaccounted for.

U.S. Pat. No. 4,118,588, assigned to BASF, is directed to a process forsynthesizing α,β-ethylenically unsaturated acids or esters such asmethacrylic acid and methylmethacrylate from the reaction of propionicacid and/or methylpropionate with dimethoxymethane (methylal) in thepresence of catalysts (most of which are acidic) based on one or moresalts selected from phosphates and silicates of: magnesium, calcium,aluminum, zirconium, thorium and titanium. Such salts can be used aloneor together with oxides of the same aforedescribed magnesium et almetals, and additionally boric acid and/or urea. Thus, a typical acidiccatalyst consists of aluminum phosphate, titanium dioxide, boric acid,and urea. Included within the list of 62 possible combinations ofvarious materials are aluminum phosphate and aluminum silicate, oraluminum phosphate, aluminum silicate, and boric acid. Such catalystscan be modified with alkali and/or alkaline earth metal: carboxylates,oxides, silicates and hydroxides. The method of catalyst preparationincludes mixing and heating the constituent components of the catalystin water, evaporating the water and drying. Other methods are disclosed,such as forming a paste, or precipitation from an aqueous solution, buteach of these alternate methods employs water as the liquid medium. Thecomponents of the catalyst are described at Col. 6, Lines 44 et seq, asbeing present in the catalyst as a mere mixture, as members of a crystallattice, or in the form of mixed crystals. This patent therefore doesnot disclose a catalyst composition of the present invention wherein thecomponents thereof have been reacted in a liquid organic medium to forman amorphous or substantially amorphous material, nor does it disclosethe method of preparing such a catalyst. The highest conversion ofmethylal reported in this patent is 92% at a selectivity (referred to inthe patent as yield) to MMA of 95% when employing catalyst of TiO₂,AlPO₄, H₂ BO₄, and urea, and a reaction time of 30 min. As describedhereinafter at Comparative Example 1, such selectivities dropdrastically when the reaction time is extended to 2.5 hours afterdiscarding the first 15 minutes of product.

U.S. Pat. No. 4,147,718, assigned to Rohm GmbH, is directed to a methodfor making α,β-unsaturated carboxylic acids and their functionalderivatives, such as methacrylic acid and methylmethacrylate, from thereaction of methylal (dimethoxymethane) with propionic acid or itscorresponding ester or nitrile, in the presence of a catalyst, whichcatalyst is a combination of silicon dioxide provided with basic sites(as described in U.S. Pat. No. 3,933,888) and aluminum oxide, whichoptionally may also be provided with basic sites in a similar manner.Aqueous impregnation procedures are employed for incorporation of thebasic sites, and the resulting basic silicon dioxide and aluminum oxidecomponents are merely then optionally mixed or arranged in separatelayers. Thus, the acid catalysts of the present invention are notdisclosed in this patent. The highest selectivity to MMA is 87.1% but ata conversion of propionic acid or methylpropionate of only 13.3%. Thehighest conversion reported is 42% at a MMA selectivity of 78%.

U.S. Pat. No. 4,324,908, assigned to SOHIO, is directed to a promotedphosphate catalyst for use in synthesizing α,β-unsaturated productss,which catalyst requires the presence of at least one or more of Fe, Ni,Co, Mn, Cu, or Ag, as promoters in conjunction with phosphorus andoxygen. The catalysts of the present invention do not require thepresence of such promoter metals in any form. The highest per passconversion of methylal to MMA+MA is 52.9% at a methylal conversion of97.6%.

Albanesi, G., and Moggi, P., Chem. Ind. (Milan) Vol. 63, p. 572-4 (1981)disclose the use of Groups 3, 4, and 5 metal oxides in unsupported, orSiO₂ supported form, for the condensation reaction between the methylhemiacetal or formaldehyde (CH₃ OCH₂ OH) and methylpropionate to formmethylmethacrylates. Ten percent WO₃ supported on SiO₂ is reported asthe best catalyst relative to other disclosed catalysts because thedecomposition of formaldehyde to CO and CO₂ and the decarboxylation ofmethylpropionate, occur least over this catalyst. However, the highestreported formaldehyde conversion when employing the tungsten catalyst isonly 37.5%. Furthermore, it is disclosed that gamma-alumina,silica-alumina and molecular sieves tend to convert the hemiacetal offormaldehyde to dimethylether and formaldehyde which in turn tend toimmediately decompose to CO and H₂ above 400° C. while in contact withthese materials.

U.S. Pat. No. 4,275,052, by the inventor herein, is directed to aprocess for synthesizing a high surface area alumina support (e.g., 300to 700 m² /g) from organic solutions of aluminum alkoxides by thehydrolysis of these alkoxides with water. In accordance with thisprocess, a first solution of an aluminum alkoxide dissolved in anorganic solvent selected from ethers, ketones, and aldehydes, is mixedwith a second solution comprising water and a similar organic solvent.The resulting material is dried and calcined, preferably in a water freeenvironment, i.e., a dry gas, since the presence of water at these stepsof the preparation will adversely affect the surface area of thealumina. The resulting alumina is used as a support or carrier materialfor catalytic components capable of promoting various hydrocarbonconversion reactions such as dehydrogenation, hydrocracking, andhydrocarbon oxidations. Conventional promoters are employed for suchreactions including platinum, rhenium, germanium, cobalt, palladium,rhodium, ruthenium, osmium and iridium. Thus, the use of these aluminasto catalyze the synthesis of α,β-unsaturated products is not disclosed.Furthermore, the reaction between aluminum alkoxide with otherhydrocarboxides, such as a silicon alkoxide, and an acidic phosphoruscompound is also not disclosed.

U.S. Pat. No. 4,233,184 is directed to an aluminum phosphate aluminacomposition prepared by mixing and reacting in the presence of moistair, an aluminum alkoxide and an organic phosphate of the formula (RO)₃PO wherein R is, for example, alkyl or aryl. The phosphorus of theresulting composition is alleged to be in the form of AlPO₄ based onx-ray analysis, but in some preparations the amorphous nature of theproduct is said to make identification of the phosphorus speciesdifficult. The amorphous nature of these samples is believed to beattributable to low calcination temperatures, e.g., below 600° C. Themole ratio of alumina to aluminum phosphate will depend upon the moleratio of aluminum alkoxide to organic phosphate employed in thesynthesis and the amount of aluminum phosphate in the final product canrange from 10 to 90% by weight. Mixed alumina-metal oxide-aluminumphosphates are also disclosed wherein a mixture of metal alkoxides canbe employed. Thus, a SiO₂ -Al₂ O₃ -AlPO₄ can be prepared from a mixtureof silicon alkoxide and aluminum alkoxide with an organic phosphate.However, from the description provided in this patent, it does notappear that the optional metal oxides (e.g. SiO₂) added initially asmetal alkoxides (e.g. silicon alkoxide) react with the organicphosphate. For example, silicon alkoxide is merely converted to thecorresponding oxide, i.e., SiO₂. This is confirmed at Col. 3, Lines 3,18, and 22, and Examples 4 to 9 wherein the optional additional metalsare reported as being present as WO₃ (Examples 4 and 5) MoO₃ (Example6), SiO₂ (Examples 7 and 8), ZrO₂ (Example 9) (see also thecharacterization of Catalyst G, Table VI). The organic phosphatesemployed in preparing the catalysts of this patent do not possess anacidic hydrogen nor is an ether, aldehyde, or ketone or mixtures thereofemployed as a solvent medium (note Example 5 of this patent employs anisopropyl alcohol organic phosphate mixture during the preparationprocedure, alcohol alone being impermissible in the present invention)as required by the present invention. The resulting composition isemployed as a catalyst or catalyst support for processes such ascracking, hydrocracking, isomerization, polymerization,disproportionation, demetallization, hydrosulfurization, anddesulfurization. Use of the composition as a catalyst for the synthesisof α,β-unsaturated products is not disclosed.

Alumina-aluminum phosphate-silica zeolite catalysts are disclosed inU.S. Pat. Nos. 4,158,621 and 4,228,036.

In view of the commercial importance rof α,β-unsaturated produucts, suchas methylmethacrylate, there has been a continuing search for catalystswhich can produce such products at improved conversions, selectivities,and/or yields. The present invention is a result of this search.

SUMMARY OF THE INVENTION

In one aspect of the present invention there is provided a process forpreparing a catalyst composition which comprises: (1) reacting inadmixture at least one Metal Hydrocarboxide I, at least one MetalHydrocarboxide II, at least one acidic phosphorus-oxygen containingcompound, and water in the presence of at least one liquid organicmedium comprising at least 50% by weight, based on the weight of saidmedium, of at least one member selected from the group consisting oforganic aldehyde, organic ketone, and organic ether, said reaction beingconducted in a manner sufficient to (a) avoid contact of MetalHydrocarboxides I and II with water prior to contact of MetalHydrocarboxides I and II with the acidic phosphorus-oxygen containingcompound and (b) form a catalyst precursor composition; (2) separatingsaid catalyst precursor composition from said reaction admixture; (3)calcining said catalyst precursor composition to form said catalystcomposition; wherein said process: (i) the metal M¹ of said MetalHydrocarboxide I is selected from at least one member of the groupconsisting of Al, Ga, In, and Tl; and (ii) the metal, M², of said MetalHydrocarboxide II is selected from at least one member of the groupconsisting of Si, Sn, and Ge.

In another aspect of the present invention there is provided a catalystcomposition prepared by the above process.

In a further aspect of the present invention there is provided a processfor using said catalyst composition to prepare α,β-ethylenicallyunsaturated acids or their acid derivatives.

DESCRIPTION OF PREFERRED EMBODIMENTS

The catalyst composition of the present invention is prepared byreacting at least one Metal (M¹) Hydrocarboxide (referred to herein asHydrocarboxide I), at least one Metal (M²) Hydrocarboxide (referred toherein as Hydrocarboxide II), at least one acidic phosphorus-oxygencontaining compound, and water in the presence of at least one liquidorganic medium under conditions and in a manner sufficient to form acatalyst precursor composition which is then calcined to form an acidiccatalyst composition. The resulting catalyst composition comprises aninorganic amorphous or substantially amorphous oxide material comprisingthe following components reacted therein:

    M.sup.1 /M.sup.2 /P/O                                      (I)

wherein M¹ is at least one Group 3b element (of the Periodic Chart)selected from Al, Ga, In, and Tl, preferably aluminum, M² is at leastone Group 4b element selected from Si, Sn, and Ge, preferably Si. Forease of discussion and description the aforedescribed Group 3b and 4belements constituting M¹ and M² are referred to generically as metals,although it is recognized that the term "metal" as applied to Si is anunconventional use of this term.

It is to be understood that the precise structure of themetal-phosphorus oxide catalysts of the present invention has not yetbeen determined although the components of the catalyst composition arebelieved to be reacted with each other during the preparative procedureand the resulting catalyst is therefore not believed to be a meremixture of oxides.

Hydrocarboxides I and II are selected to be capable of undergoinghydrolysis of the organic portion thereof in the presence of water, andcapable of being solubilized or at least partially solubilized in theorganic medium and other components of the reaction mixture.

Suitable Hydrocarboxides I which can be employed as the startingmaterial can be represented by the structural formula:

    (M.sup.1)(OR).sub.3                                        (II)

wherein M¹ is as described above, preferably Al, and R is a substitutedor unsubstituted hydrocarbyl radical independently selected from thegroup consisting of alkyl, typically alkyl having from about 1 to about8 carbons, preferably from about 2 to about 6 carbons, and mostpreferably from about 3 to about 4 carbons, aryl, typically aryl havingfrom 6 to about 14 carbons, preferably from about 6 to about 10 carbons,and most preferably 6 carbons, aralkyl, and alkaryl, typically aralkyland alkaryl wherein the alkyl and aryl portions thereof are as definedimmediately above respectively; cycloalkyl, typically cycloalkyl havingfrom about 4 to about 12 carbons, preferably from about 5 to about 10carbons, and most preferably from about 6 to about 8 carbons, all of theabove described hydrocarbyl carbon numbers being exclusive ofsubstituents; said R substituents being selected from ether groups,typically ether groups represented by the structural formulae: --O--R₁,--R₁ -- O--R₂, wherein R₁ and R₂ are independently selected from thegroup consisting of alkyl, typically about C₁ to about C₁₀ alkyl,preferably about C₁ to about C₅ alkyl, and most preferably about C₁ toabout C₃ alkyl; and ester groups, typically ester groups represented bythe structural formulae: ##STR2## wherein R₁ and R₂ are as definedabove.

Preferred Hydrocarboxide I compounds include the alkoxides.

Representative examples of suitable Hydrocarboxides I of formula IIinclude: aluminum tri: n-butoxide, sec-butoxide, isobutoxide,isopropoxide, n-propoxide, ethoxide, methoxide, phenoxide, benzoxide,nepthoxide, methoxyethoxide, 3-(methoxy carbonyl) propoxide, 3-(ethylcarbonyl oxy) butoxide, cyclohexoxide, 1,3-(dimethyl)-2-phenoxide,1,2-(methoxy)-4-benzoxide, and mixtures thereof.

Similar representative hydrocarboxides can be formed replacing part, orall of the aluminum present therein with any one or more of the otheraforedescribed Group 3b elements.

The preferred Hydrocarboxides I include aluminum: sec-butoxide,n-butoxide, n-propoxide, isopropoxide, methoxide, ethoxide; and mixturesthereof.

Hydrocarboxide II which is employed as a starting material in theprecursor forming reaction can be represented by the structural formula:

    (M.sup.2)(OR).sub.4                                        (III)

wherein M² and R are as described above in connection with structuralformulae I and II above, respectively. The specific hydrocarboxide Rgroups can be the same as illustrated above in connection with thealuminum hydrocarboxides and can be employed with any of theaforedescribed Group 4b elements.

Preferred Hydrocarboxides II include silicon: tetraethoxide,tetra-n-propoxide, tetraisopropoxide, tetramethoxide, tetra-n-butoxide,tetraisobutoxide, and mixtures thereof.

The acidic phosphorus-oxygen containing compound which can be employedas a starting material must possess at least one acidic hydrogen and becapable of reacting with the Hydrocarboxides I and II or the hydrolyzedinorganic product thereof, and the use of the term "acidic phosphorusoxygen compound" is indicative of this requirement. Representativeexamples of suitable acidic phosphorus-oxygen containing compoundsinclude phosphorus acid (P(OH)₃), phosphonous acid (HP(OH)₂),phosphinous acid (H₂ POH), phosphenous acid (O═POH), phosphoric acid(P(O)(OH)₃), phosphonic acid (HP(O)(OH)₂), phosphinic acid (H₂P(O)(OH)), phosphenic acid (O═P(O)OH), phosphine oxide (H₃ PO),phosphoranoic acid (H₄ POH), phosphorane dioic acid (H₃ P(OH)₂),phosphorane trioic acid (H₂ P(OH)₃), phosphoranetetroic acid (HP(OH)₄),phosphorane pentoic acid ((P)(OH)₅), as well as any of the aforenotedacids having one or more but not all of the acidic hydrogens replacedwith an alkyl group, typically C₁ to C₁₀, preferably C₁ to C₅ and mostpreferably C₁ to C₃ alkyl.

In addition, polyphosphoric acid, an acid commerically available as amixture of orthophosphoric acid with pryophosphoric, triphosphoric andhigher acids, sold on the basis of its calculated H₃ PO₄ content (e.g.115%), and super phosphoric acid sold at 105% H₃ PO₄ content, can alsobe employed as starting materials.

The preferred acidic phosphorus-oxygen compound is phosphoric acid.

Upon hydrolysis of Hydrocarboxides I and II and reaction with the acidicphosphorus oxygen compound, organic alcohols are formed. Since it isdesired that residual organic material in the catalyst composition beminimized, it is preferred as a matter of convenience to select theidentity of the organic moiety of the Hydrocarboxides such that thealcohols derived therefrom can be easily vaporized, e.g., alkoxideshaving fewer than about 10 carbons are most preferred.

The organic medium used in the preparation of the catalyst precursorshould be a liquid at reaction temperature and is selected from:aldehydes, ketones, ethers, and mixtures thereof typically containingfrom about 1 to about 20, preferably from about 1 to 10, and mostpreferably from about 1 to 5 carbon atoms.

More specifically, the organic moiety to which the aldehyde, ketone, andether functional groups can be attached includes alkyl, typically aboutC₁ to C₂₀, preferably about C₁ to C₁₀, most preferably about C₁ to C₅alkyl, aryl, typically about C₆ to C₁₄, preferably about C₆ to C₁₀, mostpreferably C₆ aryl, cycloalkyl, typically about C₄ to C₂₀, preferablyabout C₆ to C₁₂, most preferably about C₆ to C₁₀ cycloalkyl, aralkyl andalkaryl wherein the alkyl and aryl groups thereof are described above.

Each class of liquid organic medium can contain one or more, typically 1to 3, functional groups as well as mixtures of functional groups.Furthermore, the preferred organic moiety of liquid organic medium is asaturated aliphatic compound.

Representative aldehydes include benzaldehyde, acetaldehyde,propionaldehyde m-tolualdehyde, trioxane, valeraldehyde, butyraldehyde,oxalaldehyde, malonaldehyde, adipaldehyde.

Representative ketones include acetone, 3-pentanone, methylethylketone,cyclohexanone, dimethyl ketone, diethyl ketone, dibutyl ketone, methylisopropyl ketone, methyl sec-butyl ketone, benzophenone, and mixturesthereof.

Representative ethers include dimethyl ether, diethyl ether, dibutylether, tetrahydrofuran, anisole, dioctyl ether, 1,2-dimethoxyethane,1,4-dimethoxybutane, diethylene ether, 1,1,3,3-tetramethoxypropane, andmixtures thereof.

Preferred organic media comprise acetone, diethylether, acetaldehyde,methylethyl ketone, 3-pentanone, 1,2-dimethoxyethane and mixturesthereof.

The most preferred organic medium is acetone or a mixture of acetone anddiethylether.

The organic medium is believed to undergo electrostatic fieldinteractions with the metals of Hydrocarboxides I and II and thereaction intermediates which form upon contact of the Hydrocarboxides Iand II, the acidic phosphorus compound and water in the reactionmixture. This interaction is believed to occur through complexation ofthe organic medium with the various species present in the reactionmixture. Thus, the organic medium is not inert and only certain organicmedia have been found suitable for this purpose as described herein. Theorganic medium also functions as a solvent and/or suspending agent forthe Hydrocarboxides I and II and phosphorus containing compound, and anycomplexes and reaction intermediates thereof, as a solvent and/orsuspending agent of the resulting catalyst precursor, as a liquid forproviding uniform heating and/or mixing of the catalyst formingreactants, and as a medium capable of bringing Hydrocarboxides I and II,the phosphorus-oxygen compound, and water into intimate contact forreaction. To perform the latter function it is desirable to select theorganic medium such that it is at least miscible, preferable soluble,with or in, water, the catalyst forming reactants, and theHydrocarboxide derived alcohol. It is also preferred to select theorganic medium so that it will be completely or substantially removedfrom the catalyst precursor during drying and/or calcination. Thus,organic media with low molecular weight, and high vapor pressure arepreferred. Minor amounts of alcohol, such as the hydrocarboxide derivedalcohol can be tolerated within the organic medium initially or as itforms. Minor amounts of esters can also be included although this is notpreferred. By minor amount as used herein is meant less than 50%,preferably less than 25%, and most preferably less than 10%, by weightof the organic medium. Minor amounts of inert diluents can be employedto reduce the cost of organic medium, such as paraffins, aromaticcompounds, and mixtures thereof, although this is not preferred.

Thus, the organic medium is selected so that it is a liquid at reactiontemperature, preferably dissolves, or at least partially dissolves theprecursor forming reactants and comprises at least 50%, preferably atleast 75%, and most preferably at least 90% (e.g. 100%), by weightthereof, of any one or more of said aldehyde ketone, and ether. It ispreferred to exclude the presence of any organic alcohol, ester, or acidfrom the initial starting composition of the liquid organic medium.

The catalyst precursor forming reaction is conducted by providing areaction admixture comprising at least one Hydrocarboxide I, at leastone Hydrocarboxide II, water, and liquid organic medium. However, theorder of addition of the components is critical to the extent that itmust be conducted in a manner sufficient to avoid contact of either ofthe Hydrocarboxides I and II with water prior to contact of saidHydrocarboxides I and II with the acidic phosphorus-oxygen containingcompound, to avoid premature reaction of the water and theHydrocarboxides I and II. Thus, a wide variety of admixture sequencesare possible subject to the above constraints.

The preferred method of admixture is to initially prepare two separatesolutions typically at ambient temperature and pressure. The firstsolution contains Hydrocarboxides I and II dissolved in a suitableorganic liquid medium. The second solution contains the acidicphosphorus-oxygen compound, water, and organic liquid medium, preferablythe same medium used in, or at least miscible with, the first solution.The two solutions are then mixed preferably by the addition of solution2 to solution 1. While very small amounts of water may be tolerated inthe first solution, it is preferred that it be anhydrous. An alternativepreferred variation is to withhold a portion of the needed amount ofHydrocarboxides I and/or II from the first solution (e.g. withhold about30% by weight of the total Hydrocarboxide I and/or II, combine thesolutions and then add the remainder of Hydrocarboxide I and/or II.Stepwise addition of the Hydrocarboxides can also be accompanied withstepwise addition of organic medium. An alternative addition procedureis to prepare 3 separate solutions containing respectively.Hydrocarboxide I and liquid organic medium (Solution 1), HydrocarboxideII and liquid organic medium (Solution 2), and the acidicphosphorus-oxygen compound, water, and liquid organic medium (Solution3). The solutions are then combined simultaneously, or individually byseparately adding Solution 3 to Solutions 1 and/or 2, and admixing theresulting solutions.

The relative amounts of Hydrocarboxides I and II and acidicphosphorus-oxygen containing compound employed to form the catalystprecursor forming admixture determines the gram atom ratios of thecomponents in the catalyst. Thus, while any effective amount of saidmaterials may be initially present in said admixture, it is contemplatedthat such effective amounts constitute a mole ratio of HydrocarboxideI:Hydroocarboxide II of typically from about 1:3.5 to about 1:0.5,preferably from about 1:2 to about 1:0.7, and most preferably from about1:1.5 to about 1:0.8. The mole ratio of Hydrocarboxide I:acidicphosphorus-oxygen compound in the reaction mixture is typicallycontrolled to be from about 1:1.5 to about 1:0.5, preferably from about1:1.25 to about 1:0.7, and most preferably from about 1:1.1 to about1:0.85.

Water is also critical to the catalyst preparative process of thepresent invention. The water hydroxyzes Hydrocarboxides I and II to formalcohols and corresponding metal oxides and/or hydroxides. Consequently,the amount of water employed is related to the amount of HydrocarboxidesI and II present in the reaction admixture and preferably is effectiveto obtain complete hydrolysis thereof. Exact stoichiometric ratios,however, are not required. Thus, while any effective amount of water canbe employed to form the reaction admixture, it is contemplated that sucheffective amounts constitute a mole ratio of the sum of the moles ofHydrocarboxides I and II: H₂ O of typically from about 3:1 to about1:300, preferably from about 2:1 to about 1:10, and most preferably fromabout 1:1 to about 1:6.

The precursor forming reaction must be conducted in the presence of atleast some liquid organic medium (the composition of which is definedabove). As the amount of suitable ether, aldehyde, and/or ketone liquidorganic medium employed in the reaction mixture is decreased, theconcentration of the Hydrocarboxide derived alcohol produced in-situincreases to the extent that the aforedescribed complexation isdecreased and the undesirable effects associated with employing alcoholas the predominant organic medium during the precursor formation becomeincreasingly more pronounced, namely, the yield of the α, β-unsaturatedproducts described herein suffers drastically. The amount of organicmedium present during the precursor forming reaction is thereforeselected to effect a stirrable solution or partial solution ofreactants, and improve the yield of α, β-unsaturated product derivedfrom the use of the resulting catalyst relative to the yield of saidproduct obtainable from a catalyst prepared in the absence of saidorganic medium. Thus, while any effective amount of organic medium maybe employed, it is contemplated that such effective amount constitutetypically at least about 25%, preferably at least about 40%, and mostpreferably at least about 50%, and can range typically from about 25 toabout 95%, preferably from about 40 to about 90%, and most preferablyfrom about 60 to about 85%, by weight, of the reaction admixture, basedon the combined weight of Hydrocarboxides I and II, andphosphorus-oxygen compound, organic medium and water.

Furthermore, it is contemplated that the amount of water in the reactionmixture is controlled to be typically not greater than about 25%,preferably not greater than about 20%, and most preferably not greaterthan about 15%, and will vary typically from about 5 to about 25%,preferably from about 8 to about 20%, and most preferably from about 10to about 15%, by weight, based on the combined weight of liquid organicmedium and water in the precursor forming admixture.

The resulting admixture is preferably mixed vigorously and continuouslyduring its formation and during the reaction to effect intimate contactand reaction between the component reactants of the admixture. This canbe achieved with conventional stirring means, by refluxing or both.Thus, in a batch operation an especially convenient means of conductingthe admixing is to mechanically stir one solution while admixing into itthe other solution. In a continuous mixing operation a convenient meansof conducting the admixing is to simultaneously pump the two solutionsthrough a single means such as an in-line mixer. If reluxing is employedduring the catalyst precursor forming reaction, the liquid organicmedium is preferably selected so that it will boil at the selectedreaction temperature described hereinbelow. Removal of theHydrocarboxides I and II derived alcohol by-product by distillation canalso be employed and is preferred when large amounts of said alcoholby-product are produced in-situ.

The precursor forming reaction temperature is effective to achievecomplete reaction and is controlled in conjunction with the pressure andin a manner sufficient to avoid vaporization and loss of the essentialliquid components of the reaction admixture (e.g., excluding by-productalcohol).

Thus, while any effective temperature may be employed, it iscontemplated that such effective temperatures typically will be at least5° C., preferably at least 10° C., and most preferably at least 15° C.,and can vary typically from about 5° to about 200° C., preferably fromabout 10° to about 150° C., and most preferably from about 15° to about100° C.

The precursor forming reaction time is selected in conjunction with thereaction temperature and the amounts of Hydrocarboxides I and II topermit substantially complete reaction at the above reactiontemperatures. Such reaction times typically will vary from about 0.15 toabout 40 hours, preferably from about 0.2 to about 30 hours, and mostpreferably from about 0.5 to about 20 hours, as measured from theinitiation of contact of all of the reactive components of theadmixture. It is desired to conduct admixture of Hydrocarboxides Iand/or II with the acidic phosphorus oxygen compound to permit a slowreaction therebetween. This is typically achieved by controlling theaddition times thereof to be between about 0.5 and about 15 hours. Thereaction generally will be substantially complete after typically fromabout 0.3 to about 10, preferably from about 0.5 to about 8, and mostpreferably from about 0.5 to about 5 hours, measured from completion ofthe formation of the reaction admixture at ambient temperature. Higherreaction temperatures will cause completion of the reaction in shortertimes.

The reaction pressure is not critical provided undue loss of the liquidcontents of the reaction admixture is avoided, and can be atmospheric,subatmospheric or superatmospheric.

While not critical, upon passage of the aforedescribed reaction timesand apparent completion of the reaction, it is preferred to allow thecontents of the admixture to age for periods of typically from about 1to about 30 hours, and preferably from about 2 to about 22 hours, e.g.,at reaction temperatures of typically from about 10° to about 100° C. toassure that complete reaction has occurred.

Upon completion of the reaction and optional aging the catalystprecursor is separated from the organic medium. Generally, the organicmedium is selected so that the catalyst precursor is insoluble thereinat room temperature. Thus, precursor separation can be accomplished in avariety of ways. Typically, it takes place in two stages, namely, bybulk separation and then final purification, e.g., by drying.

Bulk separation can be accomplished by filtering the reaction admixtureto recover the catalyst precursor as a filter cake, by centrifuging thereaction admixture, and separating, e.g., by decanting, the supernatantliquid organic medium from the solid precursor, or by evaporating theliquid organic medium to form a cake or paste of the catalyst precursor.

The precursor solids, after bulk separation, are then typicallysubjected to conditions sufficient to remove any residual liquid organicmedium or any organic contaminants. This can be achieved by drying,preferably continuous drying, to evaporate residual organic liquidmedium, by washing the precursor solids with water or with an organicmedium, preferably an organic medium, having a higher vapor pressurethan the organic medium employed to form the admixture to facilitatedrying, or by employing both procedures. Thus, before final purificationis conducted, the separated catalyst precursor solids can be washed in aliquid organic medium one or more times to remove any residual unreactedmaterials and/or any other organic soluble species followed by arepetition of bulk separation procedures and then drying, although thisis not required.

Drying can be achieved by heating the precursor, e.g. by exposing theprecursor to air at a temperature of from about 20° to about 160° C. fora period of from about 0.5 to about 30 hours or by placing it in aforced circulation oven maintained at a temperature typically betweenabout 40° and about 250° C. for about 0.5 to about 30 hours.Alternatively, the precursor can be air dried at room temperature forbetween about 1 to about 40 hours and then placed in the forcedcirculation oven until constant weight is attained. Drying under reducedpressure at room or elevated temperature, such as by using a vacuum ovenis preferred.

The isolated precursor composition is then calcined to form the finalcomposition capable of catalyzing the formation of α,β-unsaturatedproducts described herein. Calcination can be conducted in a separatestep or in-situ in the reactor and involves heating the precursorcomposition to a selected temperature or temperatures within a definedtemperature range. Preferably the calcination procedure is conducted instages by heating the precursor in a stepwise fashion at increasinglyhigher temperature plateaus until a temperature of at least about 700°C. is attained.

Accordingly, and in view of the above, calcination is conducted attemperatures of typically from about 600° to about 1300° C., preferablyfrom about 650° to about 1000° C. (e.g. 650° to 850° C.), and mostpreferably from about 700° to about 1000° C. (e.g. 700° to 950° C.) fora period of typically from about 1 to about 48 hours, preferably fromabout 2 to about 30 hours, and most preferably from about 2.5 to about20 hours. Most preferably, the final temperature plateau duringcalcination will be at least 720° to about 950° C. for a period of about0.5 to about 30 (e.g. 2 to 20) hours.

However, it is preferred to subject the precursor to a precalcinationprocedure by heating it at temperatures of typically from about 400 toabout 599 and most preferably from about 450° to about 599° C., forperiods of typically from about 0.1 to about 10, and preferably fromabout 0.5 to about 8 hours. Calcination and precalcination can beconducted as two different steps as by heating first at a selectedprecalcination temperature and then at a selected calcinationtemperature or by gradually increasing the temperature from aprecalcination range to a calcination range.

The atmosphere under which calcination is conducted includes oxygen oran oxygen containing gas such as air, nitrogen, helium, or other inertgas. At the higher calcination temperatures it is preferred to includeoxygen in the calcination atmosphere.

While not essential, it is preferred that the calcination atmosphere bepassed as a moving gaseous stream over the precursor composition.

Calcination can be conducted before, after, or during intermediatestages of shaping of the catalyst precursor as described hereinafter.

The catalyst precursor or catalyst itself is adaptable to use in thevarious physical forms in which catalysts are commonly used asparticulate or powdered material in a contact bed, as a coating materialon monolithic structures generally being used in a form to provide highsurface area, as spheres, extrudates, pellets and like configurations.The precursor or catalyst, can if desired, be composited with variouscatalyst binder or support materials, or physical property modifierssuch as attrition resistance modifiers, which do not adversely affectthe catalyst or the reactions in which the catalyst is to be employed.

Thus, various sized powders can be produced by grinding the catalyst tothe desired size by any conventional or convenient means. Extrudates andpellets of various sizes and shapes can be prepared by using anyconventional or convenient means. Utilizing a conventional screw typeextruder, the dough or paste is processed through a die plate generallycomprising orifice openings in the 1/32-1/2 inch diameter range to formgenerally cylindrical particles. The freshly extruded material may becollected in the form of strands of indefinite or random lengths to bedried and subsequently broken into extrudate particles; or the freshlyextruded material may be cut into random or predetermined lengths offrom about 1/4 inch to about 1/2 inch and subsequently dried; or thefreshly extruded material may be formed into spheres, for example, bythe process whereby the extrudate strands are collected in a spinningdrum, the strands becoming segmented and spheroidized under the spinninginfluence of the drum.

While the above description of the method of preparing the catalysts ofthe present invention is provided with respect to the minimum componentswhich must be employed therein, it is contemplated that such catalystsmay have other additives (e.g. which modify the catalyst properties) orpromoters incorporated therein which typically enhance the rate and/orselectivity of the intended reaction for which the catalyst willeventually be employed to catalyze. A preferred promoter for thispurpose is boron. Catalysts of the present invention which contain boronexhibit slightly better activity at lower reaction temperatures whenemployed to catalyze the synthesis of the α, β-ethylenically unsaturatedproducts described herein. Boron can be incorporated into the catalystcomposition during preparation of the catalyst precursor or byimpregnation of the catalyst precursor or catalyst with a suitable boroncompound prior or subsequent to calcination procedures. Preferably, theboron compound is incorporated during preparation of the catalystprecursor. This can be achieved by selecting a suitable boron compoundwhich preferably is soluble in the liquid organic medium. Representativeexamples of such boron compounds include boron acetate, boronhydrocarboxides, preferably boron alkoxides, wherein the hydrocarboxideportion is as described in connection with hydrocarboxides I and II, bis(di-acetoboron) oxide, boric acid, and mixtures thereof. The boroncompound can be added to the precursor forming admixture directly or toany of the solutions which are combined to form the precursor formingadmixture.

Alternatively, a boron compound can be impregnated into the catalystcomposition by conventional means, such as by contact of the catalystcomposition with an impregnating solution having the boron compounddissolved therein. Compounds of titanium, such as, TiO₂ or titaniumhydrocarboxide similar to the hydrocarboxides disclosed herein, can alsobe included in the catalyst in a similar manner.

The catalysts of the present invention have a surface area of typicallyfrom about 40 to about 300, and preferably from about 50 to about 170 m²/g, as determined by the BET method, the general procedures and theoryfor which are disclosed in H. Brunaur, P. Emmett and E. Teller, J. ofAm. Chem. Soc. Vol. 60, p. 309 (1938).

When aluminum and silicon are employed in Hydrocarboxides I and IIrespectively, the resulting catalysts are characterized by an x-raydiffraction pattern that distinguishes them from (a) crystalline AlPO₄,and (b) a mixture of crystalline AlPO₄ and amorphous silica gel, i.e.,the primary distinguishing peaks of materials (a) and (b) immediatelyabove are absent from the x-ray spectra of the Al/Si/P/O catalysts ofthe present invention. Furthermore, in most instances, the Al/Si/P/Ocatalysts of the present invention exhibit x-ray spectra characterizedby the absence of any distinct crystalline phases, i.e., they aresubstantially amorphous within the limits of detection of the x-raydiffraction technique. This is true for materials calcined attemperatures of at least 520° C. In some instances, however, a singlelow intensity, but distinct peak is observed, indicative of the presenceof a very minor amount of crystalline material. However, this peak isnot present in the x-ray spectra of materials (a) and (b) above.

The catalysts of the present invention can be employed to improve anyone or more of the rate, conversion and selectivity of the followingwell known reaction types:

(1) The condensation, e.g., vapor phase condensation, of at least onealdehyde, or aldehyde forming compound, i.e., aldehyde precursor (e.g.methylal), with at least one carboxylic acid or derivative thereof, suchas an ester, to form α, β-unsaturated acids or esters. Such reaction canbe represented by the following equation: ##STR3## wherein R³, R⁴, andR⁵ which may be the same or different represent hydrogen, or ahydrocarbyl radical as described in conjunction with the unsubstituted Rgroup of formula II described hereinabove. Since these reactions areconducted in the vapor phase, the identity of hydrocarbyl groups R³, R⁴,and R⁵ is selected so that the respective reactants are vaporizablewithout substantial decomposition under reaction conditions. Reactant(ii) of eq. 3 can alternatively be replaced with acetals (e.g.,methylal), or hemiacetals represented by the structural formula R⁵-CH(OR⁴)₂ and R⁵ -CH(OH)OR⁴.

(2) The condensation, e.g., vapor phase condensation, of at least onecarbonyl containing compound with at least one aldehyde, acetal, and/orhemiacetal to form at least one α, β-unsaturated product as representedby the following reactions: ##STR4## wherein R³ is as described above.

(3) The esterification or hydrolysis of an ester as represented by thefollowing reversible reaction:

    R.sup.3 -CO.sub.2 H+R.sup.4 -OH⃡R.sup.3 COOR.sup.4 +H.sub.2 O (eq. 7)

wherein R³ and R⁴ are as described above.

(4) The conversion of an alcohol to an ether or hydrolysis of the etherto an alcohol as represented by the reversible reaction:

    2R.sup.3 -OH⃡R.sup.3 -O-R.sup.3 +H.sub.2 O     (eq. 8)

wherein R³ is as described above.

(5) The reaction of an ether with a carboxylic acid to form an ester andalcohol as represented by the reaction:

    R.sup.3 -COOH+R.sup.4 -O-R.sup.4 ⃡R.sup.3 -COOR.sup.4 +R.sup.4 OH                                                        (eq. 9)

(6) Other organic reactions which can be catalyzed by acidic catalysts,such as dehydration, isomerization, alkylation, cracking and the like.

Representative examples of suitable esters which can be employed in thereaction of equation 3 include methyl acetate, ethylacetate, methylpropionate, ethyl propionate, methyl n-butyrate and the methyl ester ofphenyl acetic acid. Representative acids which can be employed in thereaction of the above equations include the corresponding free acids ofthe above identified esters.

If formaldehyde is employed as a reactant in any of the aforedescribedreactions, particularly equations 3 and 4 it can be used in anyconvenient form. For example, it can be anhydrous paraformaldehyde,trioxane or in the form of an aqueous of alcoholic solution as areavailable commercially. If desired, the process may be coupled directlywith a process for the manufacture of formaldehyde or its polymers.

Processes for the production of α, β-unsaturated products in accordancewith the reaction of equations 3 to 6 are well known as describedhereinafter. Thus, starting materials (i) and (ii) of equations 3 to 6are employed in stoichiometric amounts, or in excess of either one overthe other. Accordingly, the mole ratio of starting materials (i) and(ii) of equations 3 to 6 typically can vary from about 100:1 to 1:1.5,preferably from about 50:1 to about 1:1, and most preferably from about10:1 to about 2:1.

The above reactions are preferably conducted in the vapor phase in thepresence of the catalyst of the present invention, continuously orbatchwise, in a fixed or fluid bed. The catalyst may be charged to atube or on trays or in a fluid bed, etc. through which the reactantmixture is passed. The reactor system may consist of a series ofcatalyst beds with optional interstage heating or cooling between thebeds if desired. It is also an embodiment of the invention to use eitherupflow or downflow of the reactants through the reactor, with periodicreversal of gas flow also being contemplated to maintain a cleancatalyst bed. If desired the gaseous feed may be charged together withan inert carrier gas, e.g., nitrogen, helium, argon, carbon oxides orlow molecular weight hydrocarbons.

The reaction temperature of the above reactions (eq. 3 to 6) willtypically vary from about 170 to about 450, preferably from about 200 toabout 400, and most preferably from about 250° to about 380° C., underatmospheric or superatmospheric pressure (e.g. 1 to 150 psig).

Suitable feed rates of reactants to the reaction zone typically can varyfrom about 0.2 to about 20, preferably from about 0.4 to about 10, andmost preferably from about 0.5 to about 5 hr.⁻¹ LHSV.

The following examples are given as specific illustrations of theclaimed invention. It should be understood, however, that the inventionis not limited to the specific details set forth in the examples. Allparts and percentages in the examples as well as in the remainder of thespecification are by weight unless otherwise specified.

In the following examples, unless otherwise specified, each catalyst istested in the following manner: A glass tube reactor 20 inches inlength, 1 inch O.D. and about 0.8 inch I.D., is stoppered at the bottomwith glass wool, loaded with 20 cc of catalyst sample, on top of whichis placed 10 cc of glass wool, followed by the addition of a sufficientnumber of 4 mm diameter glass balls to fill the remaining reactor tubevolume. The glass balls serve as a preheating zone about 7 inches inlength within the tube. The reactor is then mounted in a verticalfurnace having a heating chamber 2.5 cm in diameter and 30.5 cm inlength. A liquid reactant feed stream is then passed downward throughthe reactor tube at a selected furnace temperature as described herein.The feed stream is vaporized in the preheating zone and contacts thecatalyst as a vapor. All reactions are carried out under ambientatmospheric pressure. The reactant feed stream is passed through thereactor at a liquid hourly space velocity (LHSV) of 1 hr⁻¹, i.e., theliquid feed is pumped through the reactor at a rate sufficient todisplace 1 empty reactor volume of liquid every hour. The reactoreffluent for the first 15 minutes after each start-up is discarded, butis collected thereafter for a period of 2.5 hours in an ice trap. Thetotal liquid effluent collected during this time is analyzed by gaschromatography, mass spectrophotometry, and NMR. Analysis forformaldehyde, other aldehydes, and ketones is conducted by reacting therespective reaction products with o-benzylhydroxylamine hydrochlorideand sodium acetate, said reaction being conducted in the presence of atleast 55%, by weight methanol based on the weight of the mixture. Unlessother specified, the liquid reactant feed stream comprises 10%, byweight, methylal and 90%, by weight, methyl propionate, based on thetotal weight of the feed stream, and total conversion of methylal,selectivity, and yield are calculated as follows: ##EQU1## wherein theabove equations: A=moles of methylal in feed.

B=moles of methylal in reaction product.

C=moles of MMA+MA in reaction product.

D=moles of formaldehyde in reaction product.

F=formaldehyde.

MMA=methyl methacrylate.

MA=methacrylic acid.

In some examples methyl propionate is replaced with equal wt. %'s ofpropionic acid. Also, in some instances methylal is replaced by formcel,and the moles of methylal are replaced by moles of formcel in the abovecalculations.

EXAMPLE 1

Two solutions were prepared. In the first solution 155.15 g oftetraethyl orthosilicate (Si(OC₂ H₄)₄) and 115 g of aluminumtri-sec-butoxide (Al(OC₄ H₉)₃) were dissolved in 1100 cc of acetone. Thesecond solution was prepared by dissolving 50.25 g of an 85% aqueoussolution of H₃ PO₄ and 45.61 g of water in 250 cc of acetone. The secondsolution was slowly added at 25° C. to the first solution over a periodof 5 hours with continuous vigorous mechanical stirring. Aftercompletion of the addition, the reaction mixture was allowed to age atroom temperature overnight (i.e. 18 hours) with mechanical stirring. Awhite precipitate was separated from the reaction mixture by filtrationand the precipitate dried in air at 98° C. overnight in a vacuum oven.The dried solid was then calcined in air 400° C. for 1.5 hours, 450° C.for 1 hour, and then 560° C. for 3 hours. The calcined product wasground to a powder -16 mesh (Tyler sieve series). The powder, 46.54 g,was mixed with 23 g water and pelletized to 0.5 inch diameter pellets.The pellets were then calcined in air at 150° C. for 1 hour, 400° C. for30 minutes, 520° C. for 30 minutes, and then 750° C. for 3 hours. Thecalcined pellets were ground to -6+16 mesh granules and 20 cc (8.42 g)of the catalyst were tested as described above at a furnace temperatureof 350° C. Another 20 cc of catalyst were also tested at a furnacetemperature of 370° C. The results are summarized at Table 1, Run 1(furnace temp. 350° C.) and Run 2 (furnace temp. 370° C.).

EXAMPLE 2

Two solutions were prepared in general accordance with Example 1, using150.5 g of aluminum tri-sec-butoxide, 152.3 g tetraethyl orthosilicate,and 1400 cc acetone for solution 1, and 66.99 g of 85% aqueous H₃ PO₄solution, 42.62 g water, and 350 cc of acetone for solution 2. Only 60volume % of solution 2 was slowly added to solution 1 to form thereaction mixture under continuous vigorous mixing. At this point 140 ccof acetone were added to the continuously stirred reaction mixturefollowed by addition of the remaining 40 volume % of solution 2. About 5hours were required for completion of the addition of solution 2 tosolution 1. The reaction mixture was then aged overnight with mechanicalstirring. A white precipitate was separated from the reaction mixture byfiltration and dried at 90°-110° C. overnight in a vacuum oven. Thedried solid was then calcined in air at 400° C. for 1 hour, 500° C. for1 hour, and then 540° C. for 4 hours. The calcined product was ground toa powder (+16 mesh) and 21.23 g of this powder mixed with 2.02 g watersoluble starch and 14.74 g water. The resulting mixture was pelletizedand the pellets (0.5 inch diameter) calcined at 400° C. for 35 minutes,450° C. for 1.5 hours, and then 600° C. for 2.5 hours in air. Thecalcined pellets were ground to -6+16 mesh granules and the granulescalcined at 750° C. for 4 hours in air. Only part of these granules werefurther calcined at 820° C. for 4.5 hours and then 880° C. for 3.5hours. From each of the alternatively calcined catalyst samples wereremoved 20 cc, i.e., 8.70 g of Sample A calcined to a maximum of 750°C., and 8.86 g of Sample B calcined to a maximum of 880° C. Each samplewas placed in a reactor and tested as described above. The results aresummarized at Table 1, Run 3 (Sample A) and Run 4 (Sample B).

EXAMPLE 3

Two solutions were prepared in general accordance with Example 1 using133.0 g aluminum tri-sec-butoxide, 176.73 g tetraethyl orthosilicate,and 1400 cc acetone for solution 1, and 59.20 g of the 85% aqueous H₃PO₄ solution, 52.22 g water, and 350 cc acetone for solution 2. About 90volume % of solution 2 was slowly added to solution 1 at roomtemperature for a period of about 5 hours while mixing vigorously toform a reaction mixture. The resulting reaction mixture was refluxedwhile adding the remaining 10 volume % of solution 2; and the refluxingcontinued for 1.5 hours after completion of the addition. The reactionmixture was cooled to room temperature and aged overnight withmechanical stirring. A white precipitate was separated from the reactionmixture by the filteration and the filter cake dried overnight at90°-120° C. in a vacuum oven. The dried filter cake was calcined at 400°C. for 1.5 hours and then 520° C. for 4 hours in air. The calcinedproduct was ground to a powder (+16 mesh) and 28.73 g thereof mixed with0.86 g of water soluble starch and then 11.3 g water. The mixture waspelletized and the pellets (0.5 inches diameter) calcined at 430° C. for1.6 hours, 600° C. for 1.5 hours, and then 670° C. for 2 hours in air.The calcined pellets were ground to -6+16 mesh granules and the granulesfurther calcined at 750° C. for 3 hours in air. A sample of 20 cc (6.49g) of the calcined catalyst was tested as described herein and theresults summarized at Table 1, Run 5.

EXAMPLE 4

Two solutions were prepared in general accordance with Example 1, using112.90 g aluminum tri-sec-butoxide, 186.63 g tetraethyl orthosilicate,and 1400 cc acetone for solution 1, and 50.25 g of the 85% aqueous H₃PO₄ solution, 58.03 g water, and 350 cc acetone for solution 2. Solution2 was added to solution 1 to form the reaction mixture in accordancewith Example 1, with the exception that after the addition of 60 volume% of solution 2, 150 cc of acetone was slowly added to the reactionmixture, and the addition of further solution 2 resumed until 93 volume% of Solution 2 has been added. At this time the reaction mixture wasrefluxed and the remainder of solution 2 added while the reactionmixture was refluxing. The reflux was continued for an additional 1.2hours after completion of the solution 2 addition. The reaction mixturewas cooled to room temperature, aged overnight with mechanical stirringand then refluxed for an additional 3 hours. The white precipitate wasseparated from the reaction mixture by the filtration and the filtercake dried at 116° C. overnight in a vacuum oven. The dried solid wasthen calcined at 440° C. for 1.5 hours and 520° C. for 5 hours in air.The calcined filter cake was ground to a powder (+16 mesh) and 30.99 gof the powder sample were mixed with 1.48 g of water soluble starch andthen 10.20 g water. The mixture was pelletized and the pellets (0.5 inchdiameter) were calcined at 450° C. for 50 minutes, 600° C. for 1.5hours, and 670° C. for 2.7 hours in air. The calcined pellets wereground to -6+16 mesh granules, further calcined at 750° C. for 4 hours,820° C. for 4 hours, and 880° C. for 4 hours in air. A sample of 20 cc(7.00 g) of the calcined catalyst was tested as described herein and theresults summarized at Table 1, Run 6.

EXAMPLE 5

In general accordance with Example 1, two solutions were prepared using138.56 g tetraethyl orthosilicate, 59.10 g aluminum tri-sec-butoxide,and a mixture of 908 g of diethyl ether and 400 cc of acetone forsolution 1, and 26.86 g of the 85% aqueous H₃ PO₄ solution, 28.03 gwater and 200 cc of acetone for solution 2. In addition, a thirdsolution was prepared by dissolving 23.64 g of aluminum tri-secbutoxidein 200 cc of diethyl ether; and a fourth solution was prepared bydissolving 10.74 g of the 85% aqueous H₃ PO₄ solution and 12.49 g ofwater in 100 cc of acetone. Solution 2 was then gradually added tosolution 1 over a period of about 3.5 hrs. at room temperature whilestirring vigorously, to form a reaction mixture. Solution 3 was thenslowly added to the continuously agitated reaction mixture over a periodof 5 min; and the reaction mixture stirred for an additional 30 minutesupon completion of the solution 3 addition. Solution 4 was then slowlyadded to the continuously agitated reaction mixture over a period of 1hr. The reaction mixture was then aged for 18 hours at room temperatureunder continuous agitation with a magnetic stirrer. The aged reactionmixture was then refluxed for 2.17 hours, cooled to room temperature,and the white precipitate separated from the reaction mixture byfiltration. The filter cake was dried at 116° C. for 2 days in a vacuumoven and then calcined at 450° C. for 1 hour, and 520° C. for 4.5 hoursin air. The calcined filter cake was ground to a powder (+16 mesh) and46.36 g thereof, mixed with 1.3 g of water soluble starch, and then 4.98g water. The mixture was pelletized and the pellets (0.5 inch diameter)calcined at 460° C. for 1 hour, and 600° C. for 17 hours in air. Thecalcined pellets were ground to -6+16 mesh granules, and the granulesfurther calcined at 750° C. for 16 hours, and 830° C. for 4.5 hours. Theso calcined granules were then divided into two separate samples, i.e.,samples A and B. Only sample B was further calcined in air at 880° C.for 4.5 hours. Then 20 cc portions of samples A (5.80 g) and B (5.20 g)were tested as described herein, and the results summarized at Table 1,Run 7 (Sample A) and Run 8 (Sample B).

EXAMPLE 6

Two solutions were prepared in general accordance with Example 1 using116.53 g tetraethyl orthosilicate, 116.1 g aluminum tri-sec-butoxide,and 1500 cc of 1,2-dimethoxyethane solvent for solution 1, and 52.76 gof the 85% aqueous H₃ PO₄ solution, 29.18 g water, and 250 cc1,2-dimethoxyethane solvent, for solution 2. Solution 2 was added tosolution 1 in accordance with Example 1 to form the reaction mixture.After aging the reaction mixture at 25° C. for 18 hours with mechanicalstirring, and then refluxing the same for 2 hours, the white precipitatewas separated from the reaction mixture by filteration. The filter cakewas dried at 129° C. overnight in a vacuum oven and the dried filtercake calcined at 460° C. for 1.5 hours, and 520° C. for 4.5 hours inair, ground to a powder (+16 mesh), and 40.84 g thereof mixed with 1.23g of water soluble starch, and then 5.95 g water. The mixture waspelletized, and the pellets (0.5 inch diameter) calcined at 460° C. for1 hour, and then 600° C. for 17 hours in air. The calcined pellets wereground to -6+16 mesh granules and the granules further calcined at 750°for 5 hours in air. A sample of 20 cc (7.02 g) of the catalyst wastested and the result summarized at Table 1, Run 9.

EXAMPLE 7

Two solutions were prepared in general accordance with Example 1 using110.33 g tetraethyl orthosilicate, 100.45 g aluminum tri-sec-butoxide,25.5 g germanium tetraethoxide, and a mixture of 908 g absolute diethylether and 500 ml of acetone for solution 1, and 45.64 g of the 85%aqueous H₃ PO₄ solution, 36.50 g water, and 250 cc acetone for solution2. Solution 2 was added to solution 1 in accordance with Example 1 toform a reaction mixture. The reaction mixture was then aged for 18 hoursat 25° C. with mechanical stirring followed by refluxing of the same for2.5 hours. The white precipitate was separated from the reaction mixtureby filteration, and the filter cake dried at 116° C. for 2 days in avacuum oven. The dried material was then calcined at 460° C. for 1 hour,and 520° C. for 6 hours in air. The calcined filter cake was ground topowder (+16 mesh) and 44.72 g thereof mixed with 1.34 g of water solublestarch, and then 4.49 g H₂ O. The mixture was pelletized and the pellets(0.5 inch diameter) calcined at 460° C. for 1.5 hours, and 600° C. for11.5 hours in air. The calcined pellets were ground to -6+16 meshgranules and the granules further calcined at 750° C. for 4.5 hours, and820° C. for 4.5 hours in air, and 20 cc (7.0 g) of the catalyst samplewere tested and the results summarized at Table 1, Run 10.

EXAMPLE 8

Two solutions were prepared in general accordance with Example 1 using141.99 g of tetraethyl orthosilicate, 42.41 g of titanium tetrabutoxide,142.41 g of aluminum tri-sec-butoxide, and 1150 cc of acetone forsolution 1, and 62.23 g of 85% aqueous H₃ PO₄ solution, 48.20 g of waterand 300 cc of acetone for solution 2. The two solutions were combined inaccordance with Example 1 to form a reaction mixture. The reactionmixture was then aged for 18 hours at separated from the reactionmixture by filtration, the filter cake dried at 100° C. overnight in avacuum oven, and then calcined at 400° C. for 1.5 hours, 500° C. for 1hour, and 560° C. for 3 hours in air. The calcined product was ground toa powder (+16 mesh) and 40.5 g thereof mixed with 7 g of water and thenpelletized. The pellets (0.5 inch diameter) were calcined at 120° C. for1.5 hours, 300° C. for 1 hour, and 750° C. for 3 hours in air. Thecalcined product was ground to -6+16 mesh granules and 20 cc (10.40 g)of the catalyst sample tested as described herein. The results aresummarized at Table 1, Run 11.

EXAMPLE 9

A 13.56 g sample of the +16 mesh powder sample obtained from Example 5after calcination of the filter cake at 520° C. for 4.5 hours but priorto pelletizing, was mixed with 0.41 g of water soluble starch and 2.24 gwater. The mixture was pelletized and the pellets (0.5 inch diameter)calcined at 460° C. for 1 hour, and then 600° C. for 17 hours in air.The pellets were ground to -6+16 mesh granules and the granules furthercalcined at 820° C. for 5.5 hours, 880° C. for 4.5 hours, and then 930°C. for 4.5 hours in air. A 20 cc (6.07 g) catalyst sample was tested andthe results summarized at Table 1, Run 12.

EXAMPLE 10

Two solutions are prepared in general accordance with Example 1 using137.71 g of tetraethyl orthosilicate, 57.21 g aluminum tri-sec-butoxideand a mixture of 1050 cc of diethyl ether and 500 cc of acetone forsolution 1, and 26.34 g of an 85% aqueous H₃ PO₄ solution, 25.54 g waterand 200 cc acetone for solution 2. A third solution was prepared bydissolving 25.43 g aluminum tri-sec-butoxide in 150 cc of acetone, and afourth solution was prepared by mixing 11.56 g of an 85% aqueous H₃ PO₄solution with 12.64 g water and 100 cc of acetone. Solution 2 was addedslowly to solution 1 in accordance with Example 1 to form a reactionmixture. Solution 3 was then added slowly to the reaction mixture at 25°C. over a period of 5 min. and the contents thereof stirred for 0.97hours from completion of addition. Solution 4 was then slowly added tocontinuously agitated reaction mixture over a period of 1 hour, and thecontents thereof refluxed for 1.13 hours from completion of theaddition. The reaction mixture was cooled to room temperature and agedovernight with mechanical stirring. A white precipitate was separatedfrom the reaction mixture by filtration and the filter cake dried at116° C. overnight in a vacuum oven. The dried filter cake was calcinedat 450° C. for 1 hour, and 528° C. for 4 hours in air. The calcinedfilter cake was ground to a powder (+16 mesh) and 28.92 g thereof mixedwith 1.0 g of water solution starch and then 8.3 g water. The mixturewas pelletized and the pellets (0.5 inch diameter) calcined at 450° C.for 1 hour, and 600° C. for 3.3 hours in air. The calcined pellets wereground to granules (-6+16 mesh) and the granules further calcined at600° C. for 1 hour, 750° C. for 4 hours, 820° C. for 4.5 hours, and 880°C. for 4 hours in air. A 20 cc (6.34 g) catalyst sample was tested forthe condensation reaction between methylal and propionic acid. Thereaction was carried out at 350° C. furnace temperature and 1 LHSV withafeed solution of 10 wt.% methylal in propionic acid. The productanalysis showed a total methylal conversion of 100%, yield of MA+MMA of62.2%, yield of formaldehyde of 23.3%, a combined yield of MA, MMA andformaldehyde of 85.5%.

This example illustrates the effect of replacing methyl propionate withpropionic acid, namely, selectivity to MMA+MA drops only slightly,relative to the use of methyl propionate. Thus, the free acid is asutiable alternative to the corresponding ester.

EXAMPLE 11

Upon completion of catalyst testing of Sample B from Example 2, thiscatalyst was re-calcined at 600° C. for 1 hour, and then 920° C. for 4.5hours. A sample of 20 cc (9.19 g) of this material was tested as acatalyst for the condensation reaction between the methyl hemiacetal offormaldehyde and methyl propionate (known as methyl formcel andcomprising about 35 wt.% methanol, 55 wt.% formaldehyde and 10-11 wt.%H₂ O). Thus, 54.45 g of methyl formcel was mixed with 669.6 g of methylpropionate and the mixture was used for catalyst testing in accordancewith the procedures described hereinabove. The reaction was carried outat 350° C. furnace temperature and 1 hr.⁻¹ LHSV. The product analysisshowed a yield to MMA+MA of 64.0%, at a total conversion of methylformcel of 80%. This example illustrates that the methyl hemiacetal offormaldehyde is a suitable replacement for methylal in the feed stream.

EXAMPLE 12 (Part A)

Upon completion of Example 8, the catalyst employed therein wasre-calcined at 600° C. for 1 hour, and then 820° C. for 4.5 hours inair. A 20 cc (6.96 g) sample thereof was loaded in a glass tube reactor.After placing the reaction in a vertical furnace, the furnace was heatedto 350° C. and then a solution of a mixture of methyl propionate (75.41wt.%), propionic acid (9.11 wt.%), and methanol (15.48 wt.%) was pumpedinto the reactor at a 1 hr.⁻¹ LHSV feed rate. The analysis of thereactor effluent showed that decarboxylation of methyl propionate and/orpropionic acid did not occur to any detectable extent. After thisreaction, the catalyst was heated at 350° C. for 3.5 hours in a N₂ gasflow and then the following experiment was carried out.

(Part B)

The furnace was heated to 320° C., and a solution of a mixture of 35.05wt.% diethyl ether, and 64.95 wt. % propionic acid, was pumped into thereactor at a 1 hr.⁻¹ LHSV feed rate. The product analysis showed 38.7mole % propionic acid conversion to ethyl propionate and again there wasno indication of any decarboxylation of propionic acid and/or ethylpropionate. Part B of this example illustrates the use of the catalystof the present invention to catalyze Equation 9 described hereinabove.

EXAMPLE 13

Two solutions were prepared in general accordance with Example 1, using118.1 g aluminum tri-sec-butoxide, and 188.6 g tetraethyl orthosilicatedissolved in 1400 cc acetone for solution 1 and 52.57 g 85% aqueous H₃PO₄ solution, 57.34 g H₂ O, and 360 cc acetone for solution 2. At roomtemperature 88.2% of solution 2 was slowly added to solution 1 inaccordance with Example 1 with vigorous stirring. The remaining 11.8wt.% of solution 2 was added to the resulting mixture while refluxingthe latter. The reflux was continued for 1.5 hours after completing theaddition of solution 1. The reaction mixture was cooled to roomtemperature and aged 1.5 days with mechanical stirring. Whiteprecipitate was separated from the reaction mixture by the filtration,the filter cake dried at 115° C. in a vacuum oven, and then calcined at430° C. for 2 hours, and 520° C. for 4 hours in air. The calcined filtercake was ground to -20+48 mesh powder. This powder was pelletizedwithout using water and starch. Pellet size was 1/8×1/8". The pelletswere calcined at 600° C. overnight, 750° C. for 5.5 hours, 820° C. for 6hours, and then 880° C. for 5.5 hours in air.

A 20 cc (7.4 g) catalyst sample was loaded in the reactor and tested asdescribed herein in three different runs at varying feed rates andfurnace temperatures as described in Table 1. The results are summarizedat Table 1, Runs 26 to 28.

COMPARATIVE EXAMPLE 1

This comparative example is intended to illustrate the performance of atypical acidic catalyst disclosed in U.S. Pat. No. 4,118,588. Thus, 75 gTiO₂ (anatase) powder, 57.5 g AlPO₄ powder, and 18.7 g H₃ BO₃ powderwere mixed and the mixture mixed with 48.2 g aqueous urea solution,which had been prepared by dissolving 37.5 g urea in 100 g dionizedwater, to form a thick paste. The paste was dried at 120° C. for 3 hoursand then calcined at 600° C. for 3 hours. The calcined paste was groundto -6+16 mesh granules.

A 20 cc (15.89 g) catalyst sample was loaded into a glass reactor, andafter placing the reactor in a verticle furnace, a feed streamcontaining 10 wt.% methylal solution in methyl propionate was passedthrough the reactor at a flow rate of 1 hr.⁻¹ LHSV at furnacetemperatures of 350°, 370°, and 390° C. Product samples were removed ateach reaction temperature, and analyzed as described hereinabove. Theresults are summarized at Table 2, Runs 14 to 16.

COMPARATIVE EXAMPLE 2

This example is intended to illustrate the performance of a conventionalbasic catalyst such as also disclosed in U.S. Pat. No. 4,118,588. Thus,60 g of AlPO₄ powder was mixed with 4.35 g LiOH powder. The resultingmixture was mixed with 85.91 g water at about 90° C. to evaporate waterand form a solid mass. The solid mass was further dried at 210° C. for1.5 hours, and then calcined at 520° C. for 3 hours. The calcined masswas ground to -6+16 mesh granules. A 20 cc (11.82 g) sample thereof wasthen loaded into the glass reactor and tested in accordance withComparative Example 1 using the same feed stream recited therein and afurnace temperature of 350° C. (Run 17) and 370° C. (Run 18).

COMPARATIVE EXAMPLE 3

This example is intended to illustrate the performance of a basiccatalyst on the silica gel support such as illustrated in U.S. Pat. No.3,100,795 but using methylal instead of formaldehyde. Thus, 0.65 g ofKOH was dissolved in 225 g of water and 53.80 g of silica gel (-8+12mesh, 300 m² /g surface area and 1 cc/g pore volume) was impregnatedwith this KOH solution.

A 20 cc sample of the impregnated product was loaded in a glass reactorand subjected following thermal treatment in N₂ flow (800 cc/min) priorto the catalyst test:

200° C.: 1 hour

350° C.: 30 minutes

435° C.: 5 hours

Catalyst testing was carried out at 370° C. (Run 19) and 420° C. (Run20) furnace temperatures, in accordance with Comparative Example 1 andthe results summarized at Table 2, Runs 19 and 20.

COMPARATIVE EXAMPLE 4

This example is intended to illustrate the performance of an acidiccatalyst such as described in the Albanesi et al article describedabove. Thus, 36.87 g of the silica gel used in Comparative Example 3 wasimpregnated with tungstic acid solution prepared by mixing 5.04 gtungstic acid powder with 400 ml water. The impregnated product wascalcined at 410° C. for 13.5 hours, 600° C. for 5 hours, and then 880°C. for 6.5 hours. A 20 cc sample thereof was tested in accordance withComparative Example 1 at a furnace temperature of 350° C. and productsample removed and analyzed as described herein and the resultssummarized at Table 2, Run 21.

COMPARATIVE EXAMPLE 5

This example is intended to illustrate the criticality of HydrocarboxideII to catalyst composition of the present invention, by omittingtetraethyl orthosilicate therefrom. Accordingly, two solutions wereprepared in general accordance with Example 1 using 250 g of aluminumtrisec-butoxide dissolved in 1150 cc acetone for solution 1, and 102.07g of 87.8% aqueous H₃ PO₄ solution in 250 cc acetone for solution 2.Solution 2 was slowly added to solution 1 to form a reaction mixture asper Example 1. After 12 hours from completion of the solution 2addition, a white precipitate was separated by filteration and dried at98° C. overnight in a vacuum oven. The dried product was calcined at400° C. for 2 hours, and 580° C. for 3 hours in air. The calcinedproduct was ground to a power (+16 mesh) and 26.0 g thereof was mixedwith 4 g water. The mixture was pelletized (0.5 inch diameter) and thepellets calcined at 120° C. for 1 hour, 200° C. for 2.5 hours, and 600°C. for 3 hours. The calcined pellets were ground to -5+16 mesh granules.A 20 cc (9.54 g) catalyst sample was tested as in Comparative Example 1using a furnace temperature of 350° C. and the results summarized atTable 2, Run 22.

COMPARATIVE EXAMPLE 6

This example illustrates the effect on catalyst performance ofsubstituting a Group 4b metal alkoxide such as Ti for silicon.Accordingly, two solutions were prepared in general accordance withExample 1 using 320 g titanium tetrabutoxide, 160 g aluminumtri-sec-butoxide, and 1300 cc acetone for solution 1, and 71.20 g of 85%aqueous H₃ PO₄ solution, 51.32 g water and 300 cc acetone for solution2. After adding 80 volume % of solution 2 to solution 1 to form areaction mixture as per Example 1, 3.675 g of boric acid was added tothe reaction mixture under continuous agitation at 25° C., followed bythe addition of the remaining 20 volume % of solution 2 to the same.After completion of the addition (total addition time being about 5hours), the reaction mixture was aged for 18 hours at 25° C. withmechanical stirring. A white precipitate was separated from the reactionmixture by filtration and the filter cake dried at 65°-135° C. for 18hours in a vacuum oven. The dried filter cake was calcined at 200° C.for 1 hour and then 50° C. for 4 hours in air. The calcined product wasground to a powder (+16 mesh) and 146.77 g thereof mixed with 12.48 g ofwater soluble starch and then 8 g water. The mixture was extrudedthrough a 1/16 inch nozzle. The extrudate was dried and then calcined at570° C. for 3 hours in air. A 20 cc (18.94 g) catalyst sample was testedin accordance with Comparative Example 1 at a furnace temperature of350° C. and the results summarized at Table 2, Run 23.

COMPARATIVE EXAMPLE 7

This example illustrates the effect on the performance of a catalystprepared by substituting a silicon ester for the silicon alkoxide in thecatalyst preparative procedure. Accordingly, two solutions are preparedin general accordance with Example 1 using 190.53 g of silicon tetraacetate (Si(OOCCH₃)₄), 145.78 g of aluminum tri-sec-butoxide and 1450 ccof acetone, and 20.17 g bis (diacetoboron) oxide for solution 1, and63.36 g of 85% aqueous H₃ PO₄ solution, 42.42 g water, and 250 cc ofacetone for solution 2. Solution 2 was slowly added to solution 1 as perExample 1. After completion of the addition, the reaction mixture wasaged at room temperature for 18 hours with mechanical stirring. A whiteprecipitate was separated from the reaction mixture by filteration andthe filter cake dried at 90° C. for 3 hours and then at 110° C. for 18hours in a vacuum oven. The dried filter cake was calcined at 400° C.for 1.5 hours, 450° C. for 30 minutes, and then 560° C. for 3 hours inair. The calcined cake was ground to -6+16 mesh granules and had graycolor. A portion of the ground calcined cake was further calcined at750° C. for 4.3 hours and designated Sample B. The ground catalystcalcined to a maximum temperature of 560° C. is designated Sample A. A20 cc (15.40 g) portion of catalyst Sample A and a 20 cc (16.78 g)portion of catalyst Sample B were tested in accordance with ComparativeExample 1 at a furnace temperature of 350° C. and the results summarizedat Table 2, Run 24 (Sample A) and Run 25 (Sample B).

                                      TABLE 1                                     __________________________________________________________________________                   CATALYST                                                                      TESTING CONDITIONS          Selectivity                                                                          Selectivity                    Corres-                                                                            Catalyst                                                                             Reactant                                                                           Furnace                                                                            Feed Methylal                                                                            Yield of                                                                             of     of    Yield of              Run                                                                              ponding                                                                            Forming                                                                              Feed Temp.                                                                              Rate Conversion                                                                          MMA + MA                                                                             MMA + MA                                                                             F     MMA + MA              No.                                                                              Ex. No.                                                                            Reactants                                                                            Stream                                                                             (°C.)                                                                       (LHSV)                                                                             (%)   (%)    (%)    (%)   + F                   __________________________________________________________________________                                                            (%)                   1  1    (EtO).sub.4 Si                                                                       A    350  1.0  100   54.1   N/D    N/D   N/D                           Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             2  1    (EtO).sub.4 Si                                                                       A    370  1.0  100   59.5   N/D    N/D   N/D                           Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             3  2    (EtO).sub.4 Si                                                                       A    350  1.0  100   60.4   96.9   37.7  98.1                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             4  2    (EtO).sub.4 Si                                                                       A    350  1.0  100   62.1   99.0   37.3  99.4                          Al--tri-S-- B                                                                 H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             5  3    (EtO).sub.4 Si                                                                       A    350  1.0  100   59.1   90.8   34.9  94.0                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             6  4    (EtO).sub.4 Si                                                                       A    350  1.0  100   59.7   99.0   39.7  99.4                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             7  5    (EtO).sub.4 Si                                                                       A    350  1.0  100   64.1   87.0   26.1  90.5                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             8  5    (EtO).sub.4 Si                                                                       A    350  1.0  100   68.6   97.7   29.8  98.4                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             9  6    (EtO).sub.4 Si                                                                       A    350  1.0  100   56.3   94.5   40.5  96.8                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             10 7    (EtO).sub.4 Si                                                                       A    350  1.0  100   56.9   97.8   41.8  98.7                          Al--tri-S--B                                                                  Ge(OEt).sub.4                                                                 H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             11 8    (EtO).sub.4 Si                                                                       A    350  1.0  100   51.0   N/D    N/D   N/D                           Ti(OBu).sub.4                                                                 Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             12 9    (EtO).sub.4 Si                                                                       A    350  1.0  100   72.4   94.4   23.3  95.7                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             13 10   (EtO).sub.4 Si                                                                       B    350  1.0  100   62.2   81.1   23.3  85.5                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             26 13   (EtO).sub.4 Si                                                                       A    320  1.0  100   75.7   84.3   11    86.7                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             27 13   (EtO).sub.4 Si                                                                       A    310  1.0  100   74.6   91.2   18.2  92.8                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             28 13   (EtO).sub.4 Si                                                                       A    310  2.0  100   70.1   99.0   29.2  99.3                          Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                             __________________________________________________________________________     (EtO).sub.4 Si = tetraethyl orthosilicate                                     Al--triS--B = aluminum trisec-butoxide                                        Ge(OEt).sub.4 = germanium tetraethoxide                                       Ti(OBu).sub.4 = titanium tetrabutoxide                                        A = a mixture of 10% methylal and 90% methyl propionate, by weight, based     on the weight of the mixture                                                  B = a mixture of 10% methylal and 90% propionic acid, by weight, based on     the weight of the mixture                                                     N/D = not determined                                                          MMA = methyl methacrylate                                                     MA = methacrylic acid                                                         F = formaldehyde                                                         

                                      TABLE 2                                     __________________________________________________________________________                      CATALYST                                                    Corres-           TESTING CONDITIONS        Selectivity                                                                         Selectivity                    ponding                                                                             Catalyst Reactant                                                                           Furnace                                                                            Feed Methylal                                                                            Yield of                                                                           of    of    Yield of              Run                                                                              Comp. Ex.                                                                           Forming  Feed Temp.                                                                              Rate Conversion                                                                          MMA +                                                                              MMA + F     MMA + MA              No.                                                                              No.   Reactants                                                                              Stream                                                                             (°C.)                                                                       (LHSV)                                                                             (%)   MA (%)                                                                             MA (%)                                                                              (%)   + F                   __________________________________________________________________________                                                            (%)                   14 1     TiO.sub.2                                                                              A    350  1.0  91.8  16.7 N/D   N/D   N/D                            AlPO.sub.4                                                                    H.sub.3 BO.sub.3                                                              Urea                                                                 15 1     TiO.sub.2                                                                              A    370  1.0  99.1  21.3 N/D   N/D   N/D                            AlPO.sub.4                                                                    H.sub.3 BO.sub.3                                                              Urea                                                                 16 1     TiO.sub.2                                                                              A    390  1.0  100   20.8 66.0  68.5  89.3                           AlPO.sub.4                                                                    H.sub.3 BO.sub.3                                                              Urea                                                                 17 2     AlPO.sub.4                                                                             A    350  1.0  80.1  41.1 79.2  30.9  72.0                           Li OH                                                                18 2     AlPO.sub.4                                                                             A    370  1.0  85.0  39.0 75.7  34.8  73.8                           Li OH                                                                19 3     Silica gel                                                                             A    370  1.0  3.4   0    0     3.4   3.4                            impregnated                                                                   with KOH                                                             20 3     Silica gel                                                                             A    420  1.0  3.7   0    0     3.7   3.7                            impregnated                                                                   with KOH                                                             21 4     Silica gel                                                                             A    350  1.0  51.7  4.2  N/D   N/D   N/D                            impregnated with                                                              Tungstic acid                                                        22 5     Al--tri-S--B                                                                           A    350  1.0  99.6  11.1 N/D   N/D   N/D                            H.sub.3 PO.sub.4                                                              H.sub.2 O                                                            23 6     Ti(OBu).sub.4                                                                          A    350  1.0  100   35.8 N/D   N/D   N/D                            Al--tri-S--B                                                                  Boric Acid                                                                    H.sub.3 PO.sub.4                                                              H.sub.2 O                                                            24 7     Si(O.sub.2 CCH.sub.3).sub.4                                                            A    350  1.0  97.4  15.5 N/D   N/D   N/D                            Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                            25 7     Si(O.sub.2 CCH.sub.3).sub.4                                                            A    350  1.0  90.3  7.2  N/D   N/D   N/D                            Al--tri-S--B                                                                  H.sub.3 PO.sub.4                                                              H.sub.2 O                                                            __________________________________________________________________________     *See Table 1 for abbreviations                                           

DISCUSSION OF RESULTS

Referring to Table 1, it can be seen that all of the methylalconversions of Runs 1 to 12 and 26 to 28 employing methyl propionate asa co-reactant in addition to methylal are 100% at yields of MA+MMA offrom 51 to 75.7%. Such yields are achieved with the formation offormaldehyde as the predominant and re-usable by-product such that theyield of MA+MMA+Formaldehye ranges typically from 86.7 to 99.4%. Thetotal conversion of methylal simplifies the re-cycle of by-productssince only one by-product, formaldehyde, need be recycled. The highcombined selectivities to MA+MMA+F illustrate that the Cannizzaroreaction, which decomposes formaldehyde to H₂ and CO₂ is substantiallyif not completely avoided. Similarly, this data show that formaldehydedecomposition which occurs over many metal oxide catalysts as describedby Albanesi et al also is substantially avoided. The reduced performanceof the catalyst of Run 11 relative to the remainder of Runs 1 to 12 isbelieved to be attributable to dilution of the amount of HydrocarboxidesI and II in the final catalyst. The titanium diluted catalystnevertheless performs better than the catalysts of the ComparativeExamples particularly in terms of conversion. While Run 13 illustrates aslightly lower combined yield when replacing propionic acid for methylpropionate of MA+MMA+F of 85.5%, the selectivity of MA+MMA is still81.1%, the yield of MMA+MA is 62.2%, and the methylal conversion is100%.

The results of Part A of Example 12 illustrate that decarboxylation ofmethyl propionate and/or propionic acid did not occur when employing thecatalyst of the present invention.

Referring to Table 2, Comparative Example 1 illustrates the performanceof a TiO₂, AlPO₄, H₃ BO₃, urea derived acidic catalyst prepared ingeneral accordance with Example 4 of U.S. Pat. No. 4,118,588. However,contrary to the testing procedure of '588 Example 4 (reaction time 30min.), in Comparative Example 1, the initial 15 minutes of product arediscarded and the product collected thereafter for 2.5 hours was tested.The total methylal conversion was only 91.8% at 350° C. furnacetemperature and the yield of MA+MMA was only 16.7%. This contrasts witha reported 95% yield in Example 4 after immediate analysis of productfrom start-up of the '558 patent. While conversions are improved in Runs15 and 16 of Comparative Example 1 at higher furnace temperatures of370° and 390° C., MA+MMA yields still remain drastically below those ofthe present invention at about 20%.

Comparative Example 2 illustrates the performance of another catalystdisclosed in the '588 patent, namely, LiOH impregnated AlPO₄, i.e.,methylal conversions of 80 to 85% at MMA+MA yields of about 40%. Suchconversions and yields are substantially inferior to those of thepresent invention.

Comparative Example 3 illustrates an almost non-existent methylalconversion (3.4%) from a conventional basic catalyst, i.e., a KOH silicaimpregnated gel.

The tungstic acid impregnated silica gel of Comparative Example 4 alsoperforms poorly, producing a methylal conversion of only 51.7% and aMA+MMA yield of 4.2%.

The omission of silicon alkoxide from the catalyst of ComparativeExample 5 is believed to be responsible for the substantial drop inMA+MMA yield to 11.1%. It is therefore concluded that Hydrocarboxide IIis critical to the performance of the catalyst of the present invention.

Comparative Example 6 further confirms the criticality of HydrocarboxideII by substituting titanium tetrabutoxide for tetraethyl orthosilicate,and using a boron containing additive. While methylal conversion is100%, MA+MMA yield is only 35.8%.

Comparative Example 7 illustrates the criticality to the presentinvention of employing a hydrocarboxide such as an alkoxide in thecatalyst preparative procedure, instead of carbonyloxy containingorganic moiety such as silicon tetraethyl acetate. Use of the acetatestarting material in catalyst preparative method produces a MMA+MA yieldof 15.5% (Sample A) and 7.2% (Sample B). These inferior results arebelieved to be attributable to the formation of acetic acid uponhydrolysis and reaction of the silicon tetraethyl acetate with theacidic phosphorus-oxygen compound. The acetic acid coordinates morestrongly with the reaction mixture species and is therefore believed todisplace the acetone in the complexes necessary to produce the catalystsof the present invention. Furthermore, it will be noted that Sample A(calcined at 560° C.) performs better than Sample B (calcined at 750°C.). In contrast, the performance of the catalysts of the presentinvention improve with increasingly higher calcination temperaturesabove 560° C.

The principles, preferred embodiments and modes of operation of thepresent invention have been described in the foregoing specification.The invention which is intended to be protected herein, however, is notto be construed as limited to the particular forms disclosed, sincethese are to be regarded as illustrative rather than restrictive.Variations and changes may be made by those skilled in the art withoutdeparting from the spirit of the invention.

What is claimed is:
 1. A process for preparing a catalyst compositionwhich comprises:(1) reacting in admixture at least one MetalHydrocarboxide I, at least one Metal Hydrocarboxide II, at least oneacidic phosphorus-oxygen containing compound, and water in the presenceof at least one liquid organic medium comprising at least 50% by weight,based on the weight of said medium, of at least one member selected fromthe group consisting of organic aldehyde, organic ketone, and organicether, said reaction being conducted in a manner sufficient to (a) avoidcontact of Metal Hydrocarboxides I and II with water prior to contact ofMetal Hydrocarboxide I and II with the acidic phosphorus-oxygencontaining compound, and (b) form a catalyst precursor composition; (2)separating said catalyst precursor composition from said reactionadmixture; (3) calcining said catalyst precursor composition to formsaid catalyst composition;wherein said process: (i) the metal M¹, ofsaid Metal Hydrocarboxide I is selected from at least one member of thegroup consisting of Al, Ga, In, and Tl; and (ii) the metal, M², of saidMetal Hydrocarboxide II is selected from at least one member of thegroup consisting of Si, Sn, and Ge.
 2. The process of claim 1 whereinMetal Hydrocarboxide I is represented by the structural formula:

    (M.sup.1)(OR).sub.3                                        (I)

wherein M¹ is as described in claim 1, and R is at least one substitutedor unsubstituted hydrocarbyl radical independently selected from thegroup consisting of alkyl, aryl, aralkyl, alkaryl, and cycloalkyl, saidsubstituents when present on R being selected from the group consistingof ether groups, ester groups, and mixtures thereof; and MetalHydrocarboxide II is represented by the structural formula:

    (M.sup.2)(OR).sub.4                                        (II)

wherein M² is as described in claim 1 and R is independently describedin conjunction with structural formula I of claim
 2. 3. The process ofclaim 1 wherein the liquid organic medium comprises at least 75%, byweight, based on the weight of said organic medium of at least onealdehyde.
 4. The process of claim 1 wherein the liquid organic mediumcomprises at least 75%, by weight, based on the weight of said organicmedium of at least one ketone.
 5. The process of claim 1 wherein theliquid organic medium comprises at least 75%, by weight, based on theweight of said organic medium of at least one ether.
 6. The process ofclaim 1 wherein the liquid organic medium is selected from the groupconsisting of acetone, diethylether, acetaldehyde, methylethyl ketone,3-pentanone, 1,2-dimethoxyethane and mixtures thereof.
 7. The process ofclaim 1 wherein M¹ of Metal Hydrocarboxide I is Al and the M² of MetalHydrocarboxide II is Si.
 8. The process of claim 7 wherein said MetalHydrocarboxide I is at least one aluminum alkoxide, and said MetalHydrocarboxide II is at least one silicon alkoxide.
 9. The process ofclaim 1 wherein said acidic phosphorus-oxygen compound is selected fromthe group consisting of phosphorus acid, phosphonous acid, phosphinousacid, phosphenous acid, phosphoric acid, phosphonic acid, phosphinicacid, phosphenic acid, phosphine oxide, phosphoranoic acid, phosphoranedioic acid, phosphorane trioic acid, phosphoranetetroic acid, phoshoranepentoic acid, polyphosphoric acid, and mixtures thereof.
 10. The processof claim 9 wherein at least one but not all of the acidic hydrogens ofsaid acidic phoshorus-oxygen compounds are replaced with a C₁ to C₁₀alkoxide group.
 11. The process of claim 9 wherein the acidicphosphorus-oxygen compound is phosphoric acid.
 12. The process of claim1 wherein said catalyst precursor composition is calcined within atemperature range of from about 600° to about 1300° C.
 13. The processof claim 12 wherein the calcination temperature is from about 650° toabout 1000° C.
 14. The process of claim 12 wherein the calcinationtemperature is from about 700° to about 950° C.
 15. The process of claim12 wherein said catalyst precursor composition is precalcined at atemperature of from about 400° to about 599° C. prior to calcination.16. The process of claim 1 wherein boron, is incorporated into saidcatalyst composition.
 17. The process of claim 16 wherein boron isincorporated into said catalyst composition by admixing a boroncontaining compound with said reaction admixture.
 18. The process ofclaim 17 wherein said boron compound is boric acid.
 19. The process ofclaim 1 wherein not greater than 25%, by weight, water based on thecombined weight of water and liquid organic medium is present in saidreaction admixture.
 20. The process of claim 8 which comprises:(1)providing a liquid reaction admixture comprising:(a) MetalHydrocarboxide I, Metal Hydrocarboxide II, and the acidicphosphorus-oxygen containing compound at respective mole ratios of fromabout 1:3.5:1.5 to about 1:0.5:0.5; (b) water in an amount (i)sufficient to achieve a mole ratio of the sum of the moles of MetalHydrocarboxides I and II:H₂ O of from about 3:1 to about 1:300, and (ii)not greater than about 20%, by weight, based on the weight of liquidorganic medium and water in the reaction admixture; and (c) liquidorganic medium in an amount of at least about 25%, by weight, based onthe weight of said liquid admixture, said liquid organic medium beingselected to dissolve therein Hydrocarboxides I and II, and the acidicphosphorus-oxygen compound; (2) providing said liquid admixture at atemperature of from about 5° to about 200° C., for a period of fromabout 0.15 to about 40 hours in a manner sufficient to achieve intimatecontact and reaction between the Metal Hydrocarboxides I and II, water,and the acidic phosphorus-oxygen composition to form a catalystprecursor composition; (3) separating said catalyst precursorcomposition from the liquid reaction admixture thereby removing residualorganic medium from the catalyst precursor composition and recoveringthe catalyst precursor as a dry solid material; and (4) calcining saidcatalyst precursor composition solid in air within the temperature rangeof from about 650° to about 1000° C. for a period of from about 1 toabout 48 hours to form said catalyst composition.
 21. The process ofclaim 20 wherein:(a) Metal Hydrocarboxide I, Metal Hydrocarboxide II,and the acidic phosphorus-oxygen composition are present in saidadmixture at respective mole ratios of from about 1:2:1.25 to about1:0.7:0.7; (b) water is present in said reaction admixture in an amount(i) sufficient to achieve a mole ratio of the sum of the moles of MetalHydrocarboxides I and II:H₂ O of from about 2:1 to about 1:10 and (ii)not greater than about 15%, by weight, based on the weight of the liquidorganic medium and water; (c) the liquid organic medium present in saidreaction admixture comprises at least 75%, by weight, thereof of any ofsaid aldehyde, ketone, and ether, and said liquid organic mediumcomprises at least 40%, by weight of said reaction admixture based onthe weight of Hydrocarboxides I and II, the acidic phosphorus oxygencomposition, liquid organic medium and water; (d) the catalyst precursoris calcined within a temperature range of from about 700° to about 950°C.
 22. The process of claim 20 wherein the liquid organic medium asinitially added to said admixture consists essentially of said aldehyde,ketone, ether or mixtures thereof.
 23. The process of claim 20 whereinsaid catalyst precursor composition, prior to separation from the liquidreaction admixture, is aged at a temperature of from about 10° to about100° C. for a period of from about 1 to about 30 hours.
 24. The processof claim 20 wherein the catalyst precursor solids are precalcined at atemperature of from about 400° to about 599° C. for a period of fromabout 0.1 to about 10 hours prior to calcination thereof.
 25. Theprocess of claim 20 wherein said liquid reaction admixture is providedby mixing an anhydrous solution comprising Metal Hydrocarboxides I andII, and liquid organic medium, with a solution comprising the acidicphosphorus-oxygen composition, water, and liquid organic medium.
 26. Theprocess of claim 20 wherein the Metal Hydrocarboxide I is selected fromthe group consisting of aluminum tri-n-butoxide, aluminumtri-sec-butoxide, aluminum tri-isobutoxide, aluminum tri-isopropoxide,aluminum tri-n-propoxide, aluminum tri-ethoxide, and aluminumtrimethoxide and mixtures thereof; Metal Hydrocarboxide II is selectedfrom the group consisting of silicon tetraethoxide, silicontetramethoxide, silicon tetrapropoxide and mixtures thereof; the acidicphosphorus-oxygen compound is phosphoric acid; and the liquid organicmedium is selected from the group consisting of acetone, diethyletherand mixtures thereof.
 27. The process of claim 26 wherein the MetalHydrocarboxide I is aluminum sec-butoxide and Metal Hydrocarboxide II issilicon tetraethoxide.